Update language agnostic includes to use cross repo includes

[alexwolfmsft]

This pull request updates several Azure SDK authentication documentation files to use new, centralized include file paths for shared authentication content. The main goal is to standardize documentation by referencing shared content from a central location, improving maintainability and consistency across docs.

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Internal previews

📄 File	🔗 Preview link
docs/ai/get-started-app-chat-scaling-with-azure-container-apps.md	CustomerIntent: As a .NET developer new to Azure OpenAI, I want to scale my Azure OpenAI capacity to avoid rate limit errors with Azure Container Apps.
docs/ai/resources/azure-ai.md	Azure AI learning resources
docs/azure/sdk/authentication/local-development-broker.md	Authenticate .NET apps to Azure services during local development using brokered authentication
docs/azure/sdk/authentication/local-development-dev-accounts.md	docs/azure/sdk/authentication/local-development-dev-accounts
docs/azure/sdk/authentication/local-development-service-principal.md	Authenticate .NET apps to Azure services during local development using service principals
docs/azure/sdk/authentication/on-premises-apps.md	Authenticate to Azure resources from .NET apps hosted on-premises
docs/azure/sdk/authentication/system-assigned-managed-identity.md	Authenticate Azure-hosted .NET apps to Azure resources using a system-assigned managed identity
docs/azure/sdk/authentication/user-assigned-managed-identity.md	docs/azure/sdk/authentication/user-assigned-managed-identity

[Copilot]

Pull request overview

This PR updates Azure SDK authentication documentation to reference centralized cross-repo include files, aiming to standardize shared authentication content and reduce duplication.

Changes:

• Swaps local include paths in Azure authentication articles to ~/azure-dev-docs-pr/articles/includes/authentication/....
• Replaces several long, inline “sign-in” instruction blocks with centralized include files.
• Updates one link in an AI quickstart include to a docset-root-relative /dotnet/... URL.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
docs/azure/sdk/authentication/user-assigned-managed-identity.md	Switches managed identity concepts include to centralized cross-repo include.
docs/azure/sdk/authentication/system-assigned-managed-identity.md	Switches managed identity concepts include to centralized cross-repo include.
docs/azure/sdk/authentication/on-premises-apps.md	Switches app registration include to centralized cross-repo include.
docs/azure/sdk/authentication/local-development-service-principal.md	Switches multiple setup includes (app registration, group, role assignment) to centralized cross-repo includes.
docs/azure/sdk/authentication/local-development-dev-accounts.md	Switches group/role includes and replaces tool sign-in content with centralized includes.
docs/azure/sdk/authentication/local-development-broker.md	Switches broker-related includes to centralized cross-repo includes.
docs/ai/quickstarts/includes/ai-templates-azure-openai.md	Updates one internal link to a docset-root-relative /dotnet/... link.

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[gewarren]

MSDocs Build Verifier error is a false positive: dotnet/docs-tools#641